The use of UVAs by themselves or in combination with HALS to stabilize polymers such as coatings and plastics against light-induced degradation is an active area of research.
U.S. Pat. Nos. 3,118,887 and 3,268,474 disclose the stabilization of plastic and resinous compositions against the effects of ultraviolet light by incorporating therein one or more members of a class of tris-aryl triazines. It is further taught therein that at least one of the aryl groups is substituted by a hydroxyl group which is ortho to the point of attachment of the aryl group to the triazine nucleus.
U.S. Pat. Nos. 4,619,956 and 4,740,542 disclose a method of stabilizing a polymer film, coating, or a molded article against the action of light, moisture, or oxygen by incorporating aryl triazines and hindered amine light stabilizers (HALS) into said polymers. It is further disclosed that said triazines exhibited an enhanced degree of stabilization due to a synergistic effect when combined with certain hindered amine light stabilizers (HALS).
U.S. Pat. Nos. 3,244,708 and 3,896,125 describe related triazines.
Copending U.S. patent application Ser. No. 07/486,625 filed Feb. 28, 1990 describes an improved method of stabilizing polymers against the action of light. The method comprises incorporating, into a polymer, a concentrated solution of an aryltriazine. The triazine UVA of this method comprises an isomeric mixture of C.sub.6 to C.sub.12 alkyl group-containing and 2-hydroxyaryl triazines which are soluble in organic coatings solvents.
Even though aryl triazines of prior art are effective stabilizers of polymers and provide adequate protection against the action of light, moisture, and oxygen, discovery of new and more effective members of this class of ultraviolet stabilizers would be a welcome contribution to the art. It is the object of this invention to provide novel and substantially more effective aryl triazine type ultraviolet absorbers which are capable, in a synergistic combination with HALS, of stabilizing polymers such as coatings and plastics against the action of light, moisture, oxygen, or combination thereof.